Motor control for computing machines



July 29, 1941. w. A; ANDERSON 2,251,100

MOTOR' CONTROL FOR COMPUTING MACHINES Filed June 29, 1959 2 Sheets-Sheet 1 INVENTOR 4 WALTER A. ANDERSON July 29, 1941. w; A. ANDQEIRSON 2,251,100

MOTOR CONTROL FOR COMPUTING MACHINES Filed June 29, 1939 2 Sheets-Sheet 2 lull YII

5 g INVENTOR E SON 1 WALTER A ANDER -2 ATTORNEYS v-n navy 192. CLUTCHES t POWER- Qme (.PMRQL UNITED STATES PATENT OFFICE MOTOR CONTROL FOR COMPUTING HINES Walter A. Anderson. Bridgeport, Conn., assignor to Underwood Elliott Fisher Company, New York, N. Y., a corporation of Delaware Application June 29, 1939, Serial No. 281,777

MAC

3 Claims.

This invention relates to computing machines, and more particularly to improvements in the clutch mechanism of the motor drive.

The invention is an improvement on that disclosed in United States Patent No. 1,925,735, issued to Oscar J. Sundstrand on September 5, 1933.

The above patent discloses a one-revolution clutch mechanism, operable upon depression of the motor bar to close the motor circuit contacts, engage a clutch dog with a driving element to initiate a machine cycle, automatically open the motor circuit contacts near the end of the cycle, and shortly thereafter disengage the clutch dog from the driving element, ending the cycle. It has been found that frequently (due to sluggishness of certain parts) there is insufficient momentum in the driven shaft to carry the clutch dog around to the point where it is disengaged from the driving element after the motor circuit contacts are opened. This is unsatisfactory because, in order to have the contacts conditioned so that they can be closed to initiate a new cycle upon the next depression of the motor bar, it is imperative that the clutch dog be disengaged from the driving element.

It is, therefore, an object of the present invention to provide a simple and effective means for maintaining the motor circuit contacts closed until the very end of a cycle to insure positive disengagement of the clutch dog from the driving element, so that at the completion of the cycle, the parts will be in readiness to initiate the next cycle upon redepression of the motor bar.

With this and incidental objects in view, the invention consists in certain novel features of construction and combinations of parts, the essential elements of which are set forth in appended claims, and a preferred embodiment of which is hereinafter described with reference to the drawings which accompany and form part of the specification.

In the drawings:

Figure 1 is a right side elevation of the motor actuating mechanism and its connection with the drive shaft of the machine,

Figure 2 is a fragmental top plan view of the motor circuit contacts and the clutch dog stop,

Figure 3 is a detail right side elevation of the clutch drive unit with the housing cover removed, the parts being shown in normal position,

Figure 4 is a detailed sectional view taken on the line 4-4 of Figure 3, and

Figure 5 is a detail perspective view of the clutch dog and the lever that controls the opening and closing of the motor circuit contacts.

Motor drive in general The present invention is shown applied to a machine similar to the one disclosed in Patent No. 1,925,735.

The machine is operated by an electric motor I (Figure 1) under the control of a motor bar 2. Motor l is suitably secured to a housing 3, which in turn is adapted to be mounted on the base of the computing machine. The shaft of the motor is suitably connected to a worm 4 (Figures 3 and 4) extending longitudinally of the housing and journaled in bushings 4 in the opposite end walls thereof. Worm 4 meshes with a driving gear 5, freely rotatable on a driven shaft 6, extending transversely of housing 3 and journaled at one end in a bushing I in the side wall of the housing, and at its opposite end in a bushing 8 in a removable side plate 9. The right end of shaft 6 (Figure 4) is operatively connected to the main rock shaft Ill (Figure 1) of the computing machine by crank arms H and i2 fixed to shaft 6 and rock shaft to, respectively, an extension I3 being fixed to crank arm l2, and a link l4 connecting crank arm II to extension l3. Gear 5 has an extended hub l5 (Figure 4) having a series of notches I6 in its outer periphery.

The means for communicating movement from the driving gear 5 to the driven shaft 6 includes a disk I1 fixed on the outer end of the driven shaft 6. A dog l8, pivoted on a stud l9 upon the inner surface of disk H, has a depending lug 20 arranged to engage notches I6 of hub IS. A spring 2|, connected between the end of the dog and a pin 22 fixed on plate 11, constantly Clutch control mechanism The means for controlling engagement between the driving gear 5 and the driven shaft 6 comprises a plunger stop 23 mounted for reciprocal vertical movement in the top wall of housing 3 substantially in the plane of movement of dog 8. The lower end of stop 23 normally lies in the path of a lug 24, formed integral with an extended portion of dog l8. Abutment of lug 24 against stop 23 rocks dog l8 clockwise against thetnsion of spring 2|, disengaging the clutch so that normally shaft 8 is disconnected from driving gear 5. Stop 23 may be raised under the control of motor bar 2, to permit engagement between the driving and driven members.

Motor bar 2 is tensioned upwardly by a spring 25 connected between the stem of the motor bar and the machine frame. A plate 26, fixed on the stem of the motor bar, is pivoted at its lower end to a crank arm 21 of a transversely extending rod 28, mounted within a slot 29 in the base of the computing machine. The opposite end of rod 28 is pivoted to a link 3|]. The rear end of link 38 is pivoted at 3| to a bell crank 32 pivoted at 33 on side plate 9. The opposed arm of bell crank 32 is pivoted to a slide 34 that is guided for vertical movement on side plate 9. A headed stud 35, fixed on the upper end of the slide, rests within a slot in an upward extension formed on the side plate. The upper end of slide 34 is bent inwardly and rests within a slot 36 in stop 23, the inner end of the slide being bifurcated and embracing a pin 31 in stop 23 (Figure 4) When the parts are in the normal position shown in Figure 1, spring 25 serves not only to hold the motor bar in its upper position, but also, through the linkage just described, normally holds stop 23 in its lower, effective position. Upon depression of the motor bar, rod 28 rocks clockwise, pulling link 38 toward the right, in turn, rocking bell crank 32 clockwise to thrust slide 34 upwardly and raise stop 23 out of the path of lug 24, to release dog I8 for engagement with notches l6.

Motor circuit control mechanism It is desirable that the driving means be normally idle so as to prevent unnecessary wear and to conserve power. To effect this, there are provided a pair of electrical contacts 38 and 39 that are interposed in the motor circuit and arranged to be automatically closed upon the release of dog I8, and automatically opened at the very end of the cycle. Contacts 38 and 39 are suitably insulated and mounted one above the other on the top wall of housing 3. Upper contact 38 normally tends to move into contact with lower contact 39 under tension of its metal strap 4|). The strap 40 rests upon a vertically movable plunger 4| mounted in the top of housing 3. The lower end of plunger 4| rests upon a lever 42 pivoted on a stud 43 in the housing. The left end of lever 42 (Figure 3) is bent inwardly, and has a depending finger 44 (Figure having its lower edge beveled and lying in the plane of a correspondingly beveled portion 45 of dog l8 adjacent lug 24.

When the parts are in normal position. the beveled edge of finger 44 rests upon the apex of beveled portion 45 (Figures 3 and 5), holding contacts 38 and 39 open. Upon depression of motor bar 2, as dog |8 releases and swings counter-clockwise about stud I9, lever 42 immediately trips under tension of contact strap 48, permitting plunger 4| to drop and allow contacts 38 and 39 to close and complete the motor circult.

Lug 28 at this moment either engages a notch l6, or bears against the periphery of hub l5 ready to engage one of the notches. In any event, almost instantaneously with the closing of contacts 38 and 39 the clutch will engage to drive the shaft 6 and cycle the machine. The right end of lever 42 abuts the housing 3 and limits the counter-clockwise movement of the lever. As the disk I! nears the completion of its revolution, beveled portion 45 of the dog again engages the beveled edge of finger 44, raising plunger 4| to open the motor circuit. This occurs at practically the very moment that lug 24 abuts stop 23 to disengage dog I8. This insures positive disengagement of the clutch because, as will be readily apparent from Figure 3, the motor circuit contacts remain closed until the very end of the cycle.

A dog 46 pivoted on a stud 41 in the housing is maintained in wiping contact with the periphery of disk I! by a spring 48. This dog cooperates with a shoulder 49 on disk [1 to lock the disk against possible backlash incident to the sudden abutment of lug 24 against stop 23, coupled with the effect of the reverse tension exerted by spring 2|, the shoulder 49 being at such point on the disk that it is engaged by dog 48 at substantially the moment lug 24 abuts stop 23.

It has been found in practice, that the provision of this means of insuring positive disengagement of the clutch by maintaining the motor circuit closed until the very end of the cycle reduces to a minimum the necessity of adhering to fine tolerances in the manufacture of the component parts of the mechanism, and eliminates completely any possibility of the machine stalling before the completion of a cycle.

While the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form of embodiment herein disclosed, for it is susceptible of embodiment in various forms, all coming within the scope of the claims which follow.

What is claimed is:

1. A motor drive for computing machines comprising a driving and a driven element, clutch means operable to engage the driving element with the driven element, a motor circuit having a pair of switch contacts interposed therein, the contacts having means connected thereto tending normally to close the circuit, a control lever therefor, a stop for disengaging the clutch at the end of a single revolution, and means on the clutch cooperating with the lever for opening the motor contacts at the moment the clutch is disengaged.

2. In a machine of the class described, a motor drive unit including a driving element and a driven element, means for imparting movement from the driving element to the driven element, said means including a dog normally tensioned to effective engaging position, a motor circuit including a pair of lever controlled switch contacts, a stop normally in the path of the dog to place it in inefiective position, and means on the dog for opening the motor circuit contacts at the moment the dog is disengaged from the driven element.

3. In a machine of the class described, a motor drive unit including a driving member, a driven member, a dog carried by one of the members for coupling that member with the other member, an extension on the dog, a portion of which extension has a lug and an adjacent portion of which is beveled, a movable stop normally in the "I'YTS (Q POWER Qkjdlull uuun.

path of the lug to hold the dog out of effective tween the lug and the apex of the beveled porposition, a motor circuit having a pair of switch tion being such as to prevent opening of the contacts, and a lever for controlling the opening contacts until the moment the lug abuts said andolsing of said contacts, said lever having a stop.

beveled portion lying normally in the path of 5 WALTER A. ANDERSON. the beveled portion of the dog, the distance be- 

